1. Field of the Invention
The present invention relates generally to water testing systems, and more specifically, to a cross-platform web-based system for water testing capable of measuring, analyzing and maintaining the quality of water using a plurality of different test strip readers.
2. Description of the Background
Water quality is important in a variety of industries. For example, pool maintenance requires periodic regular testing of pool water and careful maintenance by chemical additives. Testing and balancing swimming pool water can be a difficult process for the owner. There are myriad test kits available with different capabilities. At minimum a suitable test kit will test for available chlorine, cyanuric acid, pH, total alkalinity, and calcium hardness. Depending on the test results the foregoing may need to be balanced. Both testing and balancing can be fraught with error and frustration.
Reagent test strips are the most common testing modality. Water test strips usually have a plurality of reagent test areas, each test area undergoing a color change in response to contact with a particular chemical constituent. The presence and concentrations of these constituents of interest can be determined by a colorimetric analysis of the color changes undergone by the test strip. Usually, this analysis involves a color comparison between the test area or test pad and a color standard or scale.
A variety of conventional test strip reading instruments exist which can determine the color change of a test strip. However, different readers employ different imagers, sample trays, differences in background lighting, different CCDs, lenses and the like, any or all of which can produce vastly different color information for the same test strip.
U.S. Pat. No. 6,614,530 to Duez et al. (Biophotonics S.A.) issued Sep. 2, 2003 shows a method for the colorimetric measurement of a defined region on an image using a color camera, and discloses color-correction of tristimulus (R, G, B) values by selection of an area within an image in order to correct the imperfection in the homogeneity of the sensor and of the illuminant.
U.S. Pat. No. 5,408,535 to Howard, III et al. (Miles, Inc.) issued Apr. 18, 1995 shows a video test strip reader for evaluating test strips that uses a video imager or camera. The reader is connectable to a computer which choreographs imaging at the proper times and calculates the test results, such as the concentration of the constituents of interest.
United States Patent Application 20120063652 to Chen et al. (Teco Diagnostics) published Mar. 15, 2012 shows a method and apparatus for color-based reaction testing of biological materials by capturing, in an uncalibrated environment, a digital image of an exposed test strip, together with an adjacently-located reference color chart or on-strip color chart. The image data specifically representing the individual test pads on the test strip, as well as the reference color blocks on the reference chart, are then located within the captured image, and compared to identify any color matches. The claims require capturing a digital image of an exposed test strip and a reference color chart in an uncalibrated environment.
U.S. Pat. No. 7,885,444 to Wang (Transpacific Systems, LLC) issued Feb. 8, 2011 shows a method for determining a response of each probe zone on a test strip by establishing a plurality of target scan lines through the pads and one “white” control line adjacent the pads, and using the white line as a reference for determining a color response of the target lines.
United States Patent Application 20100045789 by Fleming et al. published Feb. 25, 2010 shows an assay system for test strips which looks for “control” signal line(s) on the strips and conducts an assay evaluation based at least on the control signal lines.
United States Patent Application 20080034845 by Morris (Hach Co.) published Feb. 14, 2008 shows an electronic device for analyzing an aqueous solution with a housing configured to receive a test strip.
U.S. Pat. No. 6,285,454 to Douglas et al. (Mercury Diagnostics, Inc.) issued Sep. 4, 2001 shows an assay system that accurately docks a removable test strip with an optics system including an illumination LED and photodetector.
U.S. Pat. No. 8,142,722 to Morris et al. (Hach Co.) issued Mar. 27, 2012 shows a handheld portable electronic test strip tester.
U.S. Pat. No. 7,339,673 to Roman (Siemens Healthcare) issued Mar. 4, 2008 shows a miniature readhead for a photometric test strip reader.
U.S. Pat. No. 7,041,468 to Drucker et al. (TheraSense, Inc.) issued May 9, 2006 shows a blood glucose test strip receptacle for connection to a hand-held computer.
U.S. Pat. No. 8,145,431 to Kloepfer et al. (Advanced Medical Products GmbH) issued Mar. 27, 2012 shows a smart-phone-based body fluid test strip positioner. The test strip positioner positions a test strip in the FOV of the phone's camera lens to permit the camera to capture an image. A light source disposed within the positioner illuminates the analyte containing test strip to facilitate the capture of the image of the test strip. Software in the smart phone performs quantitative analysis.
United States Patent Application 20100254581 by Neeser et al. (Reveal Sciences) published Oct. 7, 2010 shows a method and apparatus for analyzing samples by obtaining an image using any mobile consumer device, storing and transmitting the image to a remote server, analyzing the image using an analysis software on a remote server, and sending the results of the analysis back to the consumer device.
U.S. Pat. No. 7,262,779 to Sones (Applied Vision Company, LLC) issued Aug. 28, 2007 shows a differential imaging colorimeter which utilizes a RGB color camera to provide accurate differential colorimetry.
United States Patent Application 20070242064 by Kuo (Asustek Computer Inc.) published Oct. 18, 2007 shows a camera used as a colorimeter and ambient light sensor.
United States Patent Application 20110275162 by Xie et al. (Alverix, Inc.) published Nov. 10, 2011 shows a low-cost assay test strip reader in which the strip is placed in a shuffle that moves it past a photodetector, which detects an optical signal at a single point. The movement of the test strip with respect to the detector allows it to scan a length of the test strip.
The foregoing references tend to rely on a fixed reference standard placed in the field of view of the camera for calibration. A fixed reference standard is not a workable solution for a cross-platform web-based system with multiple different test strip readers, all with different imaging characteristics. What is needed is a way to integrate and calibrate multiple different test strip reader types in a cross-platform cloud-based system for water testing capable of measuring, analyzing and maintaining the quality of water using any of the various test strip readers, and to obtain consistent results no matter the reader used.